FIG. 16 is a configuration diagram depicting a partial discharge sensor evaluation apparatus disclosed in Non-Patent Literature 1 illustrated below.
Upon receiving a high frequency generated by a signal source 101, a G-TEM cell 102 converts the high frequency into a substantially plane wave, and propagates the plane wave.
Thus, a partial discharge sensor 103 is irradiated with a polarized wave perpendicular to a metal surface on which the sensor is installed.
A digitizer 104 compares the intensity of a radio wave received by the partial discharge sensor 103 with that of the high frequency generated by the signal source 101 to measure a transmission characteristic from the signal source 101 to the partial discharge sensor 103.
Further, when a reference antenna with a known effective height of antenna is installed instead of the partial discharge sensor 103, the digitizer 104 measures a transmission characteristic from the signal source 101 to the reference antenna.
It is possible to determine the effective height of antenna of the partial discharge sensor 103 when the transmission characteristic from the signal source 101 to the partial discharge sensor 103 is compared with the transmission characteristic from the signal source 101 to the reference antenna.
Furthermore, it is possible to determine a frequency characteristic in the effective height of antenna when a similar measurement is performed while the frequency of the signal source 101 is varied, and a value in which these frequency characteristics are averaged at a prescribed frequency is generally used as an index for the partial discharge sensor 103.